1. Field of the Invention
The present invention concerns a device for detecting and locating anomalies in the electromagnetic protection of a system including electrical bodies and members protecting said electrical bodies and forming said electromagnetic protection.
The present invention is more particularly, although not exclusively, appropriate for a system corresponding to at least part of an aircraft such as a helicopter.
2. Description of the Prior Art
In particular, because of the increasing use in aircraft of insulative materials and materials that are poor conductors of electricity, and because of the increasing number of electrical bodies, for example cables and electrical components, that are sensitive to the electromagnetic environment, aircraft manufacturers are increasingly providing in aircraft protective members designed to protect said sensitive bodies.
These protective members are in the following forms in particular:
shielding of electrical cables to create a direct protection, or PA1 means such as high frequency seals, for example, creating localized Faraday shields in the system. PA1 firstly, all the protective members are replaced after the corresponding prescribed period of use, even if they are still serviceable, which often leads to unnecessary replacements and therefore represents an extremely high cost, and PA1 secondly, protective members that suddenly become defective, for example due to an abnormal level of stress or to an accident, are not replaced until the prescribed time, with the risk of this leading to extremely harmful consequences. PA1 document U.S. Pat. No. 5,153,524 describes a device which includes radio frequency transmitters arranged in pairs at opposite outside corners of the enclosure and a radio frequency detector situated in the interior of said enclosure which measures the sum of the energy picked up from radio frequency transmissions by each pair of transmitters, averages the values measured in this way for all of the pairs of transmitters and compares this average with a reference value to deduce any anomaly in the electromagnetic protection, and PA1 document EP-0 248 501 describes a device which is particularly suitable for monitoring a large enclosure and which includes means for generating and means for detecting a magnetic or electric field disposed on respective sides of the electromagnetic protection of the enclosure together with a data processing unit. PA1 said transmitter includes an antenna adapted to transmit an electromagnetic wave externally of said system, PA1 said receiver includes a set of sensors associated with at least some of said protective members and adapted to be protected by said protective members and to measure a representative parameter of a received electromagnetic wave, and PA1 said data processor unit is a central unit: PA1 reduces the cost of maintenance, since maintenance is carried out only for protective members that are actually defective, and PA1 increases safety, since all defective members are replaced, which is not the case with the prior art maintenance methods known in themselves and referred to hereinabove. PA1 checking can be carried out quickly and simply, and can therefore be done as frequently and as often as required or necessary; this advantage, as well as the accuracy achieved, are due in particular to the characteristics of the data processing unit, which is implemented in the form of a unit centralizing the processing operations and which compares measured values directly, rather than by averaging measured values beforehand, as in the device described in document U.S. Pat. No. 5,153,524 previously referred to; and PA1 the checking is done without physical contact, which eliminates all risk of damaging the protective members during said checking. PA1 an alarm which is triggered when an anomaly is detected, and/or PA1 a storage unit recording the measurements carried out by said sensors, in particular for subsequent exploitation, preferably on a self-contained storage medium that can be removed from said device such as a diskette, a magnetic tape or a memory cartridge.
Such protective members are naturally subject to wear due to mechanical and/or climatic stresses to which they are subjected, for example. This wear is known to be generally in direct proportion to the performance of said protective members.
Moreover, these protective members can be damaged by disturbances of the electromagnetic environment, for example by lightning.
Such wear and possible damage necessitates maintenance operations to maintain the minimal level of (electromagnetic) protection required for said system.
The maintenance operations as currently practiced generally consist in periodic replacement of all the protective members of the system, the prescribed replacement period being chosen so that the maximal wear assumed during that period cannot compromise the efficacy of the electromagnetic protection.
Such maintenance operations or replacements of protective members therefore do not take account of the actual state of wear of said protective members and have a two-fold disadvantage:
Various devices for detecting anomalies in the electromagnetic protection of an enclosure are known in themselves. In particular:
Consequently, the above prior art devices are exclusively intended to monitor a single enclosure of homogeneous construction. They cannot be used to monitor a system including a plurality of different electrical bodies and therefore cannot be used as a maintenance aid for any such system.
An object of the present invention is to remedy the above disadvantages.